The present invention relates to the field of pharmacological compositions and methods of utilizing such compositions to both treat and prevent the occurrence of otitis externa. More specifically, the present invention relates to a means of forming a barrier upon the epithelial lining of the outer ear canal so as to prevent the alkalization thereof or the introduction of bacteria therewithin while also providing a means of uniformly distributing and delivering therapeutically active agents, effective in the treatment of otitis externa, to the entire epithelial lining of said canal.
Pathological conditions can arise from, and can cause changes in surface tension values of air/liquid interfaces resident upon tissue surfaces, especially epithelial surface tissues, of and within various organs of mammalian anatomy. The naturally occurring xe2x80x9csurfactant systemxe2x80x9d secreted upon the epithelial lining of the lung which is deficient in cases of R.D.S. is known to be comprised of a complex mixture of lipids, proteins and carbohydrates (as described in a recent review: Surfactants and the Lining of the Lung, The John Hopkinds University Press, Baltimore, 1988).
The prime function of the surfactant system is to stabilize the alveoli and associated small airways against collapse by decreasing the surface tension at the air/liquid interface. It is now believed that the action of the phospholipid component of the surfactant system is the principal source of the powerful surface tension reduction effect of the naturally occurring surfactant system of the lung. More specifically, it is known that the fully saturated diacylphospholipids, principally dipalmitoyl phosphatidylcholine (DPPC), provide liquid balance and anti-collapse properties to the lung""s epithelial lining. In addition to DPPC, spreading agents, also found within the naturally occurring surfactant system, assist DPPC in rapidly forming a uniform spread film on the air/liquid surfaces of the lung. Such spreading agents include cholesteryl esters such as, for example, cholesteryl palmitate (CP); phospholipids such as, for example, diacylophosphatidylglycerols (PG), diacylphosphatidylethanolamines (PE), diacylphosphatidylserines (PS), diacylphosphatidylinositols (PI), sphingomelin (Sph) and Cardiolipin (Card) and virtually and other phospholipid, and the lysophospholipids; or any of the plasmalogens, dialklylphospholipids, phosphonolipids; carbohydrates and proteins, such as, for example, albumin, pulmonary surfactant proteins A, B, C and D. The naturally occurring surfactant system is further described in U.S. Pat. No. 5,306,483.
DPPC has been administered to infants with respiratory distress syndrome as a therapeutic measure in order to restore deficient or low levels of natural surfactant. For this purpose, DPPC has been administered by means of an aqueous aerosol generator (utilized with an incubator in which the infant resided during treatment). Endotracheal administration has also been utilized. DPPC therapy has been typified as utilizing natural surfactants (harvested from porcine or bovine lungs), or artificial, commercially synthesized compounds.
It has also heretofore been disclosed to utilize therapeutic agents, in combination with surfactant/spreading agents to effectively administer drug therapy uniformly throughout the epithelial lining of the lung. U.S. Pat. No. 5,306,483 (the xe2x80x9c""483 patentxe2x80x9d) discloses a process to prepare lipid crystalline figures in fluorocarbon propellants for the delivery of therapeutically active substances which form amorphous fluids on delivery at the air/liquid interface of the lung and which can be utilized as an effective drug delivery system. More specifically, said patent discloses a process comprising (a) preparing a mixture of one or more lipids of the group of phospholipids known as phosphatidylcholines and one or more spreading agents, in powder form and a therapeutically active substance and one or more fluorocarbon propellants, said lipids, spreading agents and therapeutically active substances being insoluble in the propellants; and (b) evaporating the propellants from the mixture. The ""483 patent teaches the combination of dipalmitoyl phosphatidylcholine (DPPC) or any of the other fully saturated Acyl chain phospholipids, 80.0 to 99.5% by weight, and other spreading agents, for example, phospholipids such as, but not limited to PG, PE, PS, PI, lysophospholipids, plasmalogens, dialkylphospholipids, diether phosphonolipids, Cardiolipin, sphingomyelin, 0.5 to 20.0% weight; neutral lipids like cholesteryl esters such as, but no limited to, cholesteryl palmitate, cholesteryl oleate, cholesteryl stearate, 0.5 to 10% by weight, carbohydrates, such as, but not limited to, glucose, fructose, galactose, pneumogalactan, dextrose, 0.5 to 10% by weight; and proteins such as, but not limited to albumin, pulmonary surfactant specific proteins A, B, C, and D 0.5 to 10% by weight, yielding lipid-crystalline structures in fluorocarbon (both chloro- and hydrofluorocarbon) propellants in which therapeutically active agents, drugs and other materials can be carried into the lungs after release from and through metered dose nebulizer. The spreading agents referred to in the ""483 patent are compounds such as the above-described phospholipids, lysophospholipids, plasmalogens, dialklyphospholipids, phosphonolipids, carbohydrates and proteins. The function of the spreading agent is to assist DPPC, or other phospholipids such as, for example, DPPG, in rapidly adsorbing and forming a spread film upon the air/liquid surfaces of the lungs. In addition, the ""483 patent also discloses a process for preparing such lipid crystalline figures in fluorocarbon propellants without a therapeutically active substance for use as a tear (as for the eye).
The outer ear canal, or, as it is also known, the external auditory canal, is lined by epithelium. It is susceptible to the same type of skin diseases as effect skin in other parts of the mammalian anatomy including, for example, eczema and psoriasis. Glands within the canal secrete a waxy exudate known as cerumen which aids in trapping air born debris as well as acidifying the epithelial surface. Such acidification, in turn, minimizes the overgrowth of bacteria. However, upon exposure to copious amounts of exogenous water such as, for instance, during swimming, the epithelial lining may become more alkaline, leading to an increased growth and over-growth in bacteria. Strains of Staphylococcus, Streptococcus and Psuedomonas species often capitalize on such alkaline conditions leading to infection and the resultant inflammatory response characteristic of infective otitis externaxe2x80x94immune mediated swelling, redness, heat and pain, often associated with a discharge which contains white blood cellsxe2x80x94. Discomfort caused by this condition ranges from a slight itch to severe pain. Temporary deafness may also result as swelling and discharge physically closes off the ear canal and prevents conduction of ambient sound to the ear drum. In addition to bacteria, fungal and viral organisms are also causative of infective otitis externa. Non-microbial antigenic material is causative of another form otitis externa specifically allergic otitis externa.
The cerumen exudate, normally secreted upon the epithelial tissue lining the external auditory canal, imparts a particularly high surface tension thereto which is useful in preventing foreign matter from reaching the tympanic membrane and effecting the middle and inner ear. In addition, inflammatory by-products, discussed in greater detail below, can further increase such surface tension. Increased surface tension is an important factor in both the symptoms and treatment of otitis externa. The epithelial wall lining the outer ear canal exhibits greater than usual surface tension during otitis externa due to the secretion thereupon of proteinaceous inflammatory response waste resulting from the lysis, phagocytosis and necrosis of antigenic material. In addition, cerumen production increases in response to inflammation of the epithelial lining of the external auditory canal. This material is highly viscous in nature. Furthermore, and also as a result of the inflammatory process, the epithelium may become extremely swollen thereby causing proximal and/or opposing walls of the auditory tube to come into close approximation of one another. As such exudate laden walls come into close proximity, the high surface tension of thereof often causes the adhesion of such opposing and/or proximal walls so as to completely close off the external auditory canal.
The closure of the external auditory canal is highly problematic in that both the treatment as well as the symptoms of otitis externa are negatively effects since such closure: i. blocks the transmission of sound to the middle ear; ii may result in painful increased pressure against the ear drum; and iii. inhibits and resists the application of medicine, through the external auditory meatus, to the effected epithelium. In addition, and even in the absence of canal closure, the afore-mentioned increased surface tensions resident upon the epithelial lining of the outer ear canal, tend to inhibit uniform application of therapeutic agents effective in the treatment of the inflammatory condition as well as such agents effective in treatment of the underlying causative antigenic trigger.
As discussed in greater detail below, antigenic material can induce, through the inflammatory response, a marked increase in cerumen secretion from the epithelial lining of the outer ear canal. In addition, the inflammatory response to increased quantities of antigenic material quite often results in increased permeability of capillaries located close to the epithelial lining. Such increased permeability results in a localized edema or swelling of the epithelial lining of the external ear canal discussed above. Such edema is the direct result of various components of blood seeping into the interstitial epithelial spaces including migration of antibody laden white cells therein where pmns may complex with the antigenic trigger of the inflammatory reaction. The resulting waste material is excreted onto the epithelial lining of the cerumen covered external auditory canal wherein said material, highly viscous in nature, greatly elevates there surface tension of the epithelial lining.
The localized edema observed as substantial swelling of the epithelial walls of the outer ear canalxe2x80x94tends to narrow this conduit between the external auditory meatus and the tympanic membrane. At the same time, the proteinaceous remnants of inflammatory phagocytosis, lysis and enzymatic destruction, discussed above, combine with the increased quantity of cerumen to form a coating upon the epithelial lining of the outer ear canal with substantially increased surface tension values.
For example, during the course of a common example of otitis externa, or xe2x80x9cswimmer""s ear,xe2x80x9d the out ear canal is filled with water. The effect of the water upon the normally acidic epithelial lining of the external auditory canal, is to overcome the bacteriostatic low ph conditions provided by healthy cerumen production, and cause alkalinization. Rising ph level of the outer canal allow bacteria, such as, for example species of staphylococcus, streptococcus and pseudomonas to multiply, overwhelm, and invade the epithelium. Water exposure may also act as a vector in introducing toxic and/or irritating chemicals into the ear canal wherein such chemicals act as antigens and/or break down the integrity of the epithelial lining of the external canal and allow bacterial, fungal and other microbial agents into the epithelial tissue.
Within the epithelium, the antigenic proteins of such bacteria or in other cases, fungal, viral or other antigenic material may come into contact with macrophages present in such tissue. Such macrophages may induce an initial immune response by presenting such antigenic material to T-lymphocytes such as, for example, a CD4+ T lymphocyte. Upon such presentation, CD4+ lymphocytes respond, in part, by releasing a multitude of interleukins and cytokines which, in turn, promote the production of increased quantities of cerumen. In addition, presentation of antigen to lymphocyte leads to a cascade of inflammatory activity wherein pmns, with activated antibody, leach out of capillaries which have been made permeable thereto by histamine, into the respiratory epithelium wherein they complex with antigen for phagcytotic, lytic and macrophagic activities. The release of arachidonic acid from such activated mast cells, macrophages and pmns may lead to, for example, the production of luekotrienes. Luekotrienes, have inflammatory effects similar to histamine. However, luekotrienes effect such chemotaxis and enhanced mucous production to a far greater degree than histamine.
Two inflammatory effects, localized edema and increased exudate surface tension act, in concert, to promote and enable the above-described attraction and adhesion of proximal epithelial surfaces to one another leading to increased blockage of the outer ear canal. However, it is the high surface tension properties of the secretions that allow and promote proximal inflamed tissues of the outer ear to remain adherent upon each other. In addition, prior to the afore-mentioned inflammatory response, it is often the effect of water causing alkalinization induced bacterial overgrowth, acting as a vector for chemical toxins/irritants, or direct effect in interrupting the epithelial barrier of the outer ear canal that allows antigen contact to initiate the above-described inflammatory cascade that comprises otitis externa.
In the past, otitis externa has been treated with the topical application of therapeutic agents demonstrating antimicrobial activity as well as anti-inflammatory action. Broad spectrum topically effective antibiotic otic suspensions containing antibacterial agents such as, for example, neomycin sulfate, colistin sulfate, polymyxin b, or combinations thereof, all broad spectrum in effect, have been utilized to destroy causative bacteria. Anti-mycotic topically acting agents such as, for example, nystatin and clotrimazole have been employed to destroy underlying fungal disease. In addition, the anti-viral agent acyclovir has been utilized to treat viral based otits externa including herpes zoster.
Anti-inflammatory agents, often included in the above-identified topically acting suspensions, have been employed to control the inflammatory process of otits externa including, for example, hydrocortisone, hydrocortisone acetate and dexamethasone sodium phosphate. Most often, the above-described therapeutically active agents are utilized in combination to treat both the causative, triggering disorder, e.g. bacterial infection, as well as the inflammatory process itself. They are also most often utilized in drop form for topical administration to the effected ear. In order to enhance a more uniform delivery of such medications to the epithelial lining of the outer ear canal, wicks, comprised of absorbent material such as, for example, cotton, are utilized to draw the suspensions into the ear canal for as complete an administration as possible. However, due to the above-described exudate present in purulent forms of otitis externa, and the cerumen present in virtually all conditions, high surface tension within the canal is resistant of uniform distribution of any of said therapeutic agents throughout the outer ear canal.
It is known that an analogous increase in surface tension occurs during episodes of otitis media. Otitis media is a pathological condition common to mammalian species, and most common to children. During episodes of otitis media, fluid accumulates in the middle ear or, as it is also known, the tympanic cavity.
Although, as described below, surfactant compositions, both natural and artificial, have been heretofore known, formulated and utilized to decrease surface tension within the lung, no such compositions, or methods for administering said compositions, have been heretofore suggested, taught or disclosed in regards to decreasing the surface tension within the lumen of the eustachian tube. Likewise, no method has heretofore been known which provides an effective decrease in opening resistance of the eustachian tube while simultaneously enhancing the pressure equilibration functions thereof.
Additionally, although such surfactant compositions have been known, formulated and utilized to decrease surface tension within the lungs, no such compositions, or methods of administering said compositions, have been heretofore suggested, taught or disclosed in regards to decreasing the surface tension of the epithelium lining the external auditory canal so as to increase the patency thereof or to utilize such methods and compositions to provide an improved and highly effective means of delivering therapeutic agents effective in the treatment of otitis externa and the above-described swelling, increased surface tension, and reduction of patency resulting from the characteristic inflammatory response thereto.
U.S. patent application Ser. No. 09/450,884, the entire disclosure of which is hereby incorporated by reference, discloses a composition and method especially formulated and adapted to increase and enhance mammalian eustachian tube lumen patency and pressure equalization performance by dramatically decreasing the surface tension of the lumenal surface of the eustachian tube. In the method and composition disclosed therein, a mixture of one or more lipids and one or more spreading agents selected from the group consisting of cholesteryl esters, phospholipids, carbohydrates, and proteins, all in powder form, and one or more fluorocarbon propellants is prepared. The lipids and the spreading agents are advantageously selected to be insoluble in the propellants. The lipids utilized in practicing said method are present in an amount of about 80 to 99.5 percent by weight and the spreading agents are present in an amount of about 0.5 to about 20 percent by weight, both based upon the total weight of the mixture. Combination of the one or more lipids, one or more spreading agents and one or more fluorocarbon propellants results in the formation of lipid crystals and described in more detail, below. A metered dose of the mixture of lipid crystals is then administered, via an external nasal orifice into a mammal upon which the present method is practiced.
Upon administration, the propellant(s) are evaporated from the mixture and the lipid crystals are deposited at a nasopharyngeal, or as it may also be described, an anterior terminus, of a subject mammalian eustachian tube whereupon said lipid crystals come into contact with lumen surfaces of the tube. Upon contact with lumen surface tissue and air/liquid interfaces of the eustachian tube lumen, the mixture of lipid crystals forms an amorphous spread film upon said air/liquid interface effectively decreasing the opening pressure thereof.
The lipid crystals deposited upon the lumen surfaces and air/liquid interface thereupon is comprised of one or more lipids which are advantageously selected to demonstrate powerful surfactant activity. In addition, the spreading agent combined therewith provides complete and uniform distribution of the surfactant over and upon the lumen air/liquid surface resulting in substantial decreases in lumen opening pressure. In turn, the decrease in lumen opening pressure results in greater patency of the eustachian tube and thereby providing a resultant increase in fluid conduction/equalizing function of this anatomical structure.
Administration of the aerosolized lipid crystals through the nasal orifice also results in deposition of said crystals upon the mucosal surfaces of the sinus passages and sinus airways. The mucosal surfaces of these airways and sinuses also demonstrates an air/liquid interface formed by the secretion of muco and muco-serous secretions thereupon. Upon deposition of the lipid crystals upon these mucosal surfaces, said crystals form a uniform and amorphous spread film and effectively reduce the surface tension thereupon. Therefore, said method and composition also contemplates reduction of the surface tension of the air/liquid surfaces resident upon mammalian sinus and sinus airway mucosal surfaces.
In a second preferred embodiment of the invention disclosed in U.S. patent application Ser. No. 09/450,884, a method of administering therapeutically active agents, effective in the treatment of otitis media, directly to mammalian eustachian tube and middle ear target tissues is disclosed. In the method of the second embodiment of said invention, a mixture of one or more lipids, one or more spreading agents, one or more therapeutically active agent(s), effective in the treatment of otitis media, and one or more fluorocarbon propellants is prepared. The one or more lipids and spreading agents are advantageously selected from the group consisting of cholesteryl esters, phospholipids, carbohydrates, and proteins, all being in powder form. The one or more lipids, spreading agents and therapeutically active agent(s), effective in the treatment of otitis media, are also advantageously selected to be insoluble in the propellants. In practicing the method of the second embodiment of the invention disclosed therein, the lipids are present in an amount of about 80 to 99.5 percent by weight and the spreading agents are present in an amount of about 0.5 to about 20 percent by weight, both based upon the total weight of said mixture. The mixture resulting from the combination of lipid(s) spreading agent(s) and therapeutically active agent and propellant forms lipid crystals which act as carriers for said therapeutically active agent. A metered dose of the mixture of lipid crystals is then administered, via an external nasal orifice, into a mammal upon which the method is practiced. A suitable bottle equipped with a metered dose valve and nasal administration adaptor is advantageously utilized for this purpose.
Upon administration of the lipid crystal mixture, the propellants, carry the lipid crystals in combination with therapeutically active agent(s) effective in the treatment of otitis media to the nasopharyngeal terminus of the eustachian tube whereupon the propellant(s) evaporate. The lipid crystals and therapeutically active agent is then deposited upon the tissues of the eustachian tube including the epithelial lined lumen whereupon the mixture forms an amorphous spread film effectively carrying said therapeutically active agent effective in the treatment of otitis media uniformly through the eustachian tube and to target tissues of the middle ear. Therefore, said composition and method are disclosed and provides for the administration of therapeutically active agents directly to lumen surfaces of mammalian eustachian tubes, and also, by means of said eustachian tube lumen, to middle ear target tissues wherein said therapeutically active agents provide effective treatment for otitis media while, in addition, providing the same increased eustachian tube patency and performance as the first embodiment.
What is needed is a composition and method providing a barrier upon the epithelial lining of the external auditory canal so as to protect same from the above-described deleterious effects of water and water-born toxins, irritants and antigenic materials. If would be further advantageous if such a composition and method was provided so as to decrease the high surface tensions associated with otitis externa so as to promote external auditory canal patency. It would be still further advantageous if a composition and method were provided for delivering therapeutically active agents, effective in the treatment of otitis externa, uniformly to the epithelial lining of the outer ear while simultaneously reducing the surface tension thereof.
Now, in accordance with the present invention, a composition for and method of preventing otitis externa is provided wherein a mixture of lipid crystals are administered to the epithelial lining of the external auditory canal whereupon said mixture of crystals forms, on contact, a uniform liquid barrier so as to prevent contact of said epithelial lining with exogenous water while simultaneously reducing the surface tension of the air/liquid interface resident thereupon.
In a first preferred embodiment of the present invention, a mixture of one or more lipids and one or more spreading agents selected from the group consisting of cholesteryl esters, phospholipids, carbohydrates[, nucleic acids] and proteins, all in powder form, and one or more fluorocarbon propellants is prepared. The lipids and the spreading agents are advantageously selected to be insoluble in the propellants. The lipids utilized in practicing the method of the present invention are present in an amount of about 80 to 99.5 percent by weight and the spreading agents are present in an amount of about 0.5 to about 20 percent by weight, both based upon the total weight of the mixture. Combination of the one or more lipids, one or more spreading agents and one or more fluorocarbon propellants results in the formation of lipid crystals and described in more detail, below. A metered dose of the mixture of lipid crystals is then administered, via and aerosol dispenser, to the external auditory canal through the external auditory meatus of a mammal upon which the present method is practiced.
Upon administration, the propellant(s) are evaporated from the mixture and the lipid crystals are deposited upon the air/liquid interface resident upon the epithelial lining of the external auditory canal whereupon said lipid crystals form an amorphous spread film thereupon so as to effectively decrease the surface tension thereof as well as to form a barrier against exogenous water thereupon.
The lipid crystals deposited upon the epithelial surfaces lining the external auditory canal and the air/liquid interface thereupon is comprised of one or more lipids which are advantageously selected to demonstrate powerful surfactant activity. In addition, the spreading agent combined therewith provide complete and uniform distribution of the surfactant over and upon the air/liquid surface resident upon said lining. In turn, the decrease in surface tension afforded thereby tends to separate proximal and opposing epithelial of the external auditory canal adherent, one upon the other, so as to increase patency of said conduit and promote sound conduction therethrough. In addition, said decrease in surface tension also minimizes and, in some instances, eliminates the collection of fluids therewithin which might otherwise also serve to occlude, or partially occlude said external auditory canal. Administration of the aerosolized lipid crystals through the external auditory meatus results in deposition of said crystals upon the epithelial lining of the entire external auditory canal without need for the use of conduction devices such as, for example, wicks.
In a second preferred embodiment of the present invention, a method of administering therapeutically active agents effective in the treatment of otitis externa including both agents effective in treatment of inflammation as well as those agents effective in the treatment of the agents causative thereofxe2x80x94directly to the effected epithelial liningxe2x80x94is disclosed. In the method of the second embodiment of the present invention, a mixture of one or more lipids, one or more spreading agents, one or more therapeutically active agent(s), effective in the treatment of otitis external and/or the underlying cause thereof, and one or more fluorocarbon propellants is prepared. The one or more lipids and spreading agents are advantageously selected from the group consisting of cholesteryl esters, phospholipids, carbohydrates, proteins and all being in powder form. The one or more lipids, spreading agents and therapeutically active agent(s) are also advantageously selected to be insoluble in the propellants. In practicing the method of the second embodiment of the present invention, the lipids are present in an amount of about 80 to 99.5 percent by weight and the spreading agents are present in an amount of about 0.5 to about 20 percent by weight, both based upon the total weight of said mixture. The mixture resulting from the combination of lipid(s) spreading agent(s) and therapeutically active agent and propellant forms lipid crystals which act as carriers for said therapeutically active agent. A metered dose of the mixture of lipid crystals is then administered, via the external auditory meatus, into the external auditory canal of a mammal upon which the method is practiced. A suitable bottle equipped with a metered dose valve and otic adaptor is advantageously utilized for this purpose.
Upon administration of the lipid crystal mixture, the propellants, carry the lipid crystals in combination with therapeutically active agent(s) effective in the treatment of inflammation as well as those agents effective in the treatment of the underlying causes thereof directly to, and uniformly upon, the epithelial lining of the external auditory canal. The lipid crystals and therapeutically active agent(s) are then deposited upon said epithelial tissue lining whereupon the mixture forms an amorphous spread film effectively carrying said therapeutically active agent effective in the treatment of the inflammation characteristic of otitis externa and/or the underlying cause thereof, uniformly therethrough and thereupon.
As stated in further detail below, the therapeutically active agent is advantageously selected to be effective in the treatment of otitis externa as well as agents effective in the treatment of the underlying causes thereof provoking said immune responses leading to the above-described inflammatory responses. For example, such agents may be selected to be effective in the treatment of mycotic, viral or bacterial infections, (as well as combinations thereof) underlying and causative of said inflammatory reactions. Therefore, the second preferred method of the present invention provides a method of administering therapeutically active agents directly to the epithelial lining of the external auditory canal wherein said therapeutically active agents provide effective treatment for the subject inflammatory condition such as, for example edema as well as the underlying causes thereofxe2x80x94while, simultaneously, the mixture of lipid crystals act to directly and effectively decrease the surface tension of cerumen and, especially in instances of purulent otitis externa, the viscous mucous exudate thereupon.
The lipid crystals deposited upon the air/liquid interface of said epithelial lining is comprised of one or more lipids which are advantageously selected to demonstrate powerful surfactant activity and to serve as a carrier for selected therapeutic agent(s). In addition, the spreading agent deposited therewith provides complete and uniform distribution of the surfactant and therapeutic agent(s) throughout the lining of the external auditory canal resulting in an increase in patency thereof.
In some instances, more than one such agent may be carried by means of the lipid crystals. Such agents are contemplated to be antibiotics, anti-viral agents, anti-inflammatory agents (steroid and non-steroid) anti-histamines and decongestants as well as combinations thereof.
The lipids utilized in practicing the method of the present invention may be advantageously selected to be phospholipids, neutral lipids or mixtures thereof. The phospholipids utilized may be further advantageously selected to be any phospholipid of the class known as phosphatidlycholine including any fully saturated diacyl phosphatidlycholine including 1,2 dipalmitoyl phosphatidylcholine (DPPC); a diacylphosphatidylglycerol; a diacylphosphatidylethanolamine; a diacylphosphatidylserine; a diacylphosphatidylinositol; sphingomyelin, Cardiolipin, lysophospholipid; a plasmalogen; a diether phosphonolipid; or a dialklyphospholipid.
The cholesteryl esters utilized in practicing the method of the present invention may be advantageously selected to be cholesteryl palmitate, cholesteryl oleate or cholesteryl stearate. Carbohydrates utilized in the present invention may be advantageously selected to be glucose, fructose, galactose, pneumogalactan, or dextrose. Proteins especially suited and advantageously selected for use in the present invention include albumin, pulmonary surfactant specific proteins A or B or C or D, their synthetic analogs, and mixtures thereof.
The fluorocarbon propellants may be advantageously selected to be chlorofluorocarbon propellants, hydrofluorocarbons or mixtures thereof. In addition, the present invention contemplates carbon dioxide as a suitable propellant. The mixture is advantageously prepared to yield crystalline forms that demonstrate a particle size equal to or less than 16 microns in diameter. The diminutive nature of the crystalline particles is, as discussed in detail below, highly advantageous in enabling dispersion and application of the aerosolized mixture.
The therapeutically active agent(s) referred to throughout this disclosure and in the claims refer to those agents, discussed in detail below that effectively reduce or eliminate the subject inflammatory effects as well as agents that treat the underlying precipitating factors thereof as discussed here-above and hereafter.
Throughout this specification and claims, the phrase xe2x80x9ctherapeutically active agentxe2x80x9d includes any substance which is capable of altering a biologic, physiologic and/or immunologic function, in nature or degree and includes those substances generally referred to as pharmacologic agents and drugs, including nucleic acids utilized in gene therapy, in order to provide treatment of the symptoms or underlying causes of the subject inflammation; the term xe2x80x9cfluorocarbonsxe2x80x9d includes the class of both chlorofluorocarbons and- hydrofluorocarbons; the term lipids includes the class of phospholipids including, but not limited to PC, PG, PE, PI and Cardiolipin; and the phrase xe2x80x9cspreading agent(s)xe2x80x9d refer to and includes PG, PE, PS, PI, Sph., Card., lysophospholipids, plasmalogens, dialkylphospholipids, and all others in the class phospholipid as well as cholesteryl esters (like CP), proteins and carbohydrates.
Throughout this specification and claims, the phrase xe2x80x9cspreading agent(s)xe2x80x9d refers to compounds, as listed above, which assist the one or more lipid such as, for example, DPPC, in rapidly adsorbing and forming an amorphous spread film on air/liquid interfaces such as that found upon the epithelial lined lumen of the auditory tube. In addition, the compounds referred to as xe2x80x9cspreading agent(s)xe2x80x9d, together with the one or more lipids, are responsible for achieving and maintaining biophysical properties including, but not limited to, reduction of intermolecular attractive forces, surface tension, and the resultant attractive forces generated thereby, that tend to cause opposed surfaces, such as proximal and opposing epithelial lined walls of the external auditory tube, to adhere to each other.
The major lipid component utilized in practicing a preferred embodiment of the present invention is advantageously selected to be phospholipid 1,2 dipalmitoyl, phosphatidlycholine (DPPC). DPPC is the most surface active of the phospholipids or any of the subclass of fully saturated acyl chain phospholipids. That is to say that DPPC, in combination with any spreading agent(s) disclosed herein, has a maximum effect in reducing surface tension at an air/liquid interface.
Another, minor lipid component that also acts as a spreading agent for the major component is advantageously selected to be diacylphosphatidylglycerol (PG). The number of carbon atoms in the acyl chains R and Rxe2x80x2, (see PG formula below) can vary between 8 and 22 and may or may not be fully saturated. DPPC and PG can be synthesized. However, since DPPC and PG are the main phospholipid constituents of cells, they are also readily extractable from such cells by non-polar solvents, i.e., chloroform, ether, acetone. DPPC""s structural formula is: 
and PG""s structural formula is: 
Phospholipids such as DPPC and CP may be obtained commercially, in a highly purified form from Fluka Chemical Co. of Ronkonkoma, N.Y.; Sigma Chemical CO. of St. Louis Mo.; and Avanti Polar Lipids of Birmingham, Ala. and Primedica of Cambridge, Mass.
DPPC and PG are preferred component(s) advantageously utilized in the present inventions methods for administering therapeutically active agents to the external auditory canal. In addition, these lipids increase the patencey of the auditory tube by direct action of their surfactant qualities. DPPC may be selected to be present in the composition over a fairly wide range. Percentages of DPPC may be s as low as 70% and as high as 99.5% of the lipids by weight with little change in the in-vitro properties, and the effectiveness of the present method. However, 99.5% DPPC by weight is selected for the preferred embodiment.
Throughout this disclosure and within the claims, the terms xe2x80x9cincreasing the patency of the external auditory canalxe2x80x9d, xe2x80x9creducing obstruction of the external auditory canalxe2x80x9d, and xe2x80x9creduction of resistance to sound conductionxe2x80x9d, all refer to the opening, and elimination of blockage of the external auditory canal so as to form a patent conduit between the external auditory meatus and the tympanic membrane. The resistance referred to results from: reduction of the volume, partial obstruction, or complete occlusion of the external auditory canal due to swelling of the epithelial walls thereof as the result of inflammation; reduction of the volume, partial obstruction or complete obstruction of said air ways and air spaces due to the accumulation of increased amounts of cerumen secreted thereupon; and reduction of the volume, partial obstruction or complete obstruction of said outer air canal due to the collection of fluids therewithin including fluids containing the waste products of the immune response or exogenous waterxe2x80x94.
In those embodiments of the present invention wherein the aerosolized mixture of lipid crystals does not include, or act as a carrier for, a therapeutically active agent(s), the above-described reduction in obstruction of the external auditory canal is brought about by the separation of proximal and or opposing epithelial surfaces lining the canal and collection of fluids there between by means of decreasing the surface tension thereupon. The terms xe2x80x9cproximal epithelial surfaces lining the external auditory canalxe2x80x9d and xe2x80x9cproximal epithelial surfaces lining the external auditory canalxe2x80x9d and xe2x80x9copposing epithelial wallsxe2x80x9d as utilized throughout this specification and throughout the claims, refers to portions of the epithelial surface lining the outer auditory tube that, due to close proximity and/or opposition to each other, may come into contact as the result of, for example, epithelial or sub-epithelial edema, excess surface secretion of cerumen, inflammatory waste products or a combination thereof; high surface tension or any combination thereof.
In those instances where the aerosolized mixture of lipid crystals does include and act as a carrier for a therapeutically active agent(s), the above-described reduction in resistance to air flow is brought about by: lowering the surface tension of proximal/opposing epithelial walls of and decreasing the pooling of secretions within said conduit by means of said lipid crystals; and by reducing or temporarily halting the inflammatory response causing the edema, and excess viscous secretions by i. direct anti-inflammatory effect, ii. by reducing or eliminating the triggering factor of said inflammation, or iii. by combinations thereof.
For example, in those instances of the present invention wherein an anti-inflammatory is the therapeutically active agent, proximal walls of epithelial lining of the outer ear canal that are adherent to each other are separated and opened by means of both lipid crystal mediated reduction of surface tension and, upon action of said anti-inflammatory, reduction of edema, reduction of cerumen, and decrease in the viscous nature thereof.
Another lipid that can be utilized in practicing the methods of the present invention is cholesteryl palmitate(CP), which also serves as a spreading agent. This cholesteryl ester is a neutral lipid which belongs to a class of organic compounds that are also cell constituents and are extractable by non-polar solvents such as chloroform, methanol, ether, etc. The structural formula of CP is: 
CP may be obtained commercially in a highly purified form from Fluka Chemical Co. and Sigma Chemical Co and Primedica. The CP component constitutes a minor portion of the composition, since it is selected to be present in an amount ranging from 0.5% to 10% by weight. Also, the preferred ratio of DPPC to CP is 99.5 DPPC to 0.5 CP by weight. However, the percentages may be altered within that range without undue interference in desired properties needed for drug delivery and surfactant activity.
The term xe2x80x9ctherapeutically active agents effective in the treatment of otitis externaxe2x80x9d as utilized in and throughout this specification and claims, refers to those drugs effective in direct treatment of the above-described inflammatory response, as well as those drugs effective in the treatment of the underlying or precipitating cause of such inflammation. In the case of infective otitis externa, a therapeutically active agent may be selected for its particular effectiveness against viral, protozoic, bacterial, fungal and/or parasitic organisms. In cases of allergic otitis externa, such therapeutic effective agents may be selected for direct effect upon inflammation as there is no precipitating organism responsible for said condition. Therefore, the present invention contemplates embodiments which include as a therapeutic agent, singly or in combination: drugs effective in the direct treatment of inflammation such as, for example, corticosteroids including, for example, hydrocortisone, hydrocortisone acetate and dexamethasone sodium phosphate, betamethasone, betamethasone dipropionate and betamethasone valerate as well as all other effective formulations. It is also contemplated that embodiments of the present invention include, as a therapeutically active agent, anti-viral agents such as, for example zovirax; antibiotics including, for example, neomycin sulfate, colistin sulfate, polymyxin b, and anti-mycotic preparations such as nystatin and clotrimazole. It is further contemplated that certain embodiments of the present invention include combinations of anti-inflammatory agents and anti-microbial agents, the inclusion of a single or multiple antibiotic being determined by the sensitivity of an identified a causative underlying micro organism, as determined by culture and sensitivity studies. The term xe2x80x9call of their effective formulationsxe2x80x9d as used throughout this specification and in the claims refers to those specific species of a particular therapeutic agent effective in the treatment of the above-described inflammation and/or underlying causative agent. It is also contemplated that said therapeutically effective agents include nucleic acids as well as the vectors thereof as utilized in gene therapy.
The combination of lipid component(s) and spreading agent component(s) disclosed herein, may be referred to, collectively, as the xe2x80x9ccarrierxe2x80x9d when said combination is mixed with a therapeutically active agent so as to act as a carrier therefore. When practicing the method of the present invention wherein therapeutically active agents are administered directly to the epithelial lining of the external auditory canal, it is preferred that carrier, the mixture of one or more lipids and one or more spreading agents, be comprised of a mixture of DPPC and CP in a 200:1 ratio (by weight). However, it has been found that a ratio range of from 5:1 to 300:1 (DPPC/CP) will also produce an effective carrier for this embodiment. If, for example, the therapeutic agent is selected to be betamethasone, the weight ratio of betamethasone to carrier (DPPC/CP) is advantageously selected to be 1 microgram betamethasone to 5 milligrams carrier. However, it has been found that a weight ratio range of 0.5 to 1000 micrograms betamethasone/5 milligrams carrier yields an effective and functional mixture.
When practicing the method of the present invention wherein the therapeutically active agent is selected to be hydrocortisone acetate it is preferred to select the weight ratio of hydrocortisone to carrier to be 1.0 milligram/4.0 milligrams. However, it has also been found that a weight ratio range of from 0.005 to 1.5 milligrams (hydrocortisone): 4.995 to 3.5 milligrams carrier, respectively, forms an effective mixture and functional mixture. The term xe2x80x9ceffective and functional mixturexe2x80x9d as utilized throughout this application and in the claims refers to the effectiveness of the mixture of lipid crystals in combination with said therapeutically active agent resulting from the combinations disclosed herein in: (a) reaching the target tissue of the epithelium of the external auditory canal; (b) reducing the surface tension thereupon; and (c) delivering a uniform dose of therapeutic agent directly to and spreading uniformly upon and throughout the epithelium so as to effectively bring symptomatic relief and/or resolution of the afore-mentioned pathological conditions underlying otitis externa as well as acting, by means of said lipid crystals to open and increase the patency of said conduit by reduction of surface tension and elimination of pooled fluids therewithin.
When practicing the method of the present invention wherein the therapeutically active agent is selected to be the antibiotic neomycin sulphate, the ratio of neomycin to carrier is advantageously selected to be 0.4 mg antibiotic to 4.6 mg carrier (DPPC/CP) by weight. However, a weight range of from 0.1 to 1 mg neomycin: from 4.9 to 4.0 mg carrier, respectively, has been found to be fully effective in practicing the present method.
The fluorocarbon propellants utilized in practicing the method of the present invention, namely: trichlorodifluoromethane, dichlorodifluoromethane, and tetrafluoromethane or mixtures thereof, which are commercially available from Union Carbide Corp., Danbury, Conn. and Armstrong Laboratories, West Roxbury Mass. are advantageously selected for formation of the lipid crystalline figures of the present invention. The fluorocarbon propellants are present over a range of 2 to 30 times the amount, by weight, of lipid, but components of lipid and fluorocarbon propellants both are needed in order to obtain the required lipid crystalline figures.
In practicing the methods of the present invention wherein therapeutically effective agents are administered directly to the epithelial lining of the external auditory tube, DPPC is advantageously selected as the major lipid component since the amphoteric nature of this phospholipid allows the molecule to act as a carrier for any drug or therapeutic agent. However, the presence of a charge on other lipid components (a negative charge on PG, for example) would alter and further improve the carrying capacity of the lipid crystals for a particular therapeutic agent.
Because of the highly amphoteric nature of the carrier utilized herein, the use of any presently known and available, as well as anti-viral, antibiotic or gene therapy developed in the future capable of providing effective treatment of infections of the upper respiratory tract are contemplated and fully functional with the methods and compositions herein.